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      <a id="comb"></a>
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      <a id="IndexComb" class="indexterm"></a>
      <div class="refnamediv">
        <h2>
          <span class="refentrytitle">comb</span>
        </h2>
        <p>comb — 
      Reverberates an input signal with a <span class="quote">“<span class="quote">colored</span>”</span> frequency response.
          </p>
      </div>
      <div class="refsect1">
        <a id="idp94918992"></a>
        <h2>Description</h2>
        <p>
      Reverberates an input signal with a <span class="quote">“<span class="quote">colored</span>”</span> frequency response.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp94920752"></a>
        <h2>Syntax</h2>
        <pre class="synopsis">ares <span class="command"><strong>comb</strong></span> asig, krvt, ilpt [, iskip] [, insmps]</pre>
      </div>
      <div class="refsect1">
        <a id="idp94922960"></a>
        <h2>Initialization</h2>
        <p>
      <span class="emphasis"><em>ilpt</em></span> -- loop time in seconds, which
      determines the <span class="quote">“<span class="quote">echo density</span>”</span> of the
      reverberation. This in turn characterizes the
      <span class="quote">“<span class="quote">color</span>”</span> of the <span class="emphasis"><em>comb</em></span> filter
      whose frequency response curve will contain
      <span class="emphasis"><em>ilpt</em></span> * <span class="emphasis"><em>sr</em></span>/2 peaks
      spaced evenly between 0 and <span class="emphasis"><em>sr</em></span>/2 (the
      Nyquist frequency). Loop time can be as large as available
      memory will permit. The space required for an
      <span class="emphasis"><em>n</em></span> second loop is
      <span class="emphasis"><em>n</em></span>*<span class="emphasis"><em>sr</em></span> floating or
      double numbers (usually 4 or 8 bytes). Delay space is allocated
      and returned as in <a class="link" href="delay.html" title="delay"><em class="citetitle">delay</em></a>.
    </p>
        <p>
      <span class="emphasis"><em>iskip</em></span> (optional, default=0) -- initial disposition of delay-loop data space (cf. <a class="link" href="reson.html" title="reson"><em class="citetitle">reson</em></a>). The default value is 0.
    </p>
        <p>
      <span class="emphasis"><em>insmps</em></span> (optional, default=0) -- delay amount, as a number of samples.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp94996128"></a>
        <h2>Performance</h2>
        <p>
      <span class="emphasis"><em>krvt</em></span> -- the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude).
    </p>
        <p>
      This filter reiterates input with an echo density determined by loop time <span class="emphasis"><em>ilpt</em></span>. The attenuation rate is independent and is determined by <span class="emphasis"><em>krvt</em></span>, the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude). Output from a comb filter will appear only after <span class="emphasis"><em>ilpt</em></span> seconds.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp95000048"></a>
        <h2>Examples</h2>
        <p>
      Here is an example of the comb opcode. It uses the file <a class="ulink" href="examples/comb.csd" target="_top"><em class="citetitle">comb.csd</em></a>.

      </p>
        <div class="example">
          <a id="idp95001904"></a>
          <p class="title">
            <strong>Example 127. Example of the comb opcode.</strong>
          </p>
          <div class="example-contents">
            <p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
            <pre class="programlisting">
<span class="csdtag">&lt;CsoundSynthesizer&gt;</span>
<span class="csdtag">&lt;CsOptions&gt;</span>
<span class="comment">; Select audio/midi flags here according to platform</span>
-odac     <span class="comment">;;;RT audio out</span>
<span class="comment">;-iadc    ;;;uncomment -iadc if RT audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o comb.wav -W ;;; for file output any platform</span>
<span class="csdtag">&lt;/CsOptions&gt;</span>
<span class="csdtag">&lt;CsInstruments&gt;</span>

<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">ksmps</span> <span class="op">=</span> 32
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
<span class="ohdr">0dbfs</span> <span class="op">=</span> 1

gamix <span class="opc">init</span> 0 

<span class="oblock">instr</span> 1 

kcps    <span class="opc">expon</span> p5, p3, p4
asig	<span class="opc">vco2</span>  0.3, kcps
	<span class="opc">outs</span>  asig, asig 

gamix <span class="op">=</span> gamix <span class="op">+</span> asig 

<span class="oblock">endin</span>

<span class="oblock">instr</span> 99 

krvt <span class="op">=</span>  3.5
ilpt <span class="op">=</span>  0.1
aleft	<span class="opc">comb</span> gamix, krvt, ilpt
aright	<span class="opc">comb</span> gamix, krvt, ilpt<span class="op">*</span>.2
	<span class="opc">outs</span>   aleft, aright

<span class="opc">clear</span> gamix	<span class="comment">; clear mixer</span>
 
<span class="oblock">endin</span>

<span class="csdtag">&lt;/CsInstruments&gt;</span>
<span class="csdtag">&lt;CsScore&gt;</span>

<span class="stamnt">i</span> 1 0 3 20 2000
<span class="stamnt">i</span> 1 5 .01 440 440

<span class="stamnt">i</span> 99 0 8
<span class="stamnt">e</span>

<span class="csdtag">&lt;/CsScore&gt;</span>
<span class="csdtag">&lt;/CsoundSynthesizer&gt;</span>
</pre>
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        <p><br class="example-break" />
    </p>
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      <div class="refsect1">
        <a id="idp95006224"></a>
        <h2>See Also</h2>
        <p>
      <a class="link" href="alpass.html" title="alpass"><em class="citetitle">alpass</em></a>,
      <a class="link" href="reverb.html" title="reverb"><em class="citetitle">reverb</em></a>,
      <a class="link" href="valpass.html" title="valpass"><em class="citetitle">valpass</em></a>,
      <a class="link" href="vcomb.html" title="vcomb"><em class="citetitle">vcomb</em></a>
    </p>
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        <a id="idp95011216"></a>
        <h2>Credits</h2>
        <p>
      </p>
        <table border="0" summary="Simple list" class="simplelist">
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            <td>Barry L. Vercoe</td>
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